1. Field of the Invention
The present invention relates to an ink jet recording apparatus for recording onto a recording sheet by discharging the ink thereto, and more particularly to an ink jet recording apparatus and method with the improvement of selecting the driving voltage optimal for the discharge heater provided in the recording head, or capable of achieving the proper recording in accordance with the number of ink tanks which have been used.
2. Related Background Art
Today, a wide variety of information recording apparatuses such as printers, facsimiles and word processors have been developed. As one of the recording methods for such recording apparatuses, an ink jet method has been widely used owing to its advantages such as high resolution, high speed recording, low cost, and compact size. In particular the compact size of the apparatus and the reduction in operating cost are important factors.
In a conventional ink jet recording apparatus, there is mounted an ink jet head unit 701 consisting of an ink discharge port 702, and a substrate 703 having signal contacts 704 and heater voltage ID circuits 705 as shown in FIGS. 1A and 1B.
The heater voltage for determining the ink discharge rate is selected from four values of heater voltage in order to compensate for production variations in heater resistance of the ink jet head unit 701. The selection of the heater voltage can be performed by a combination of cutting the four wiring patterns 706 for heater voltage ID circuit 705. An ink jet recording apparatus selects a heater voltage optimal for a recording head that has been exchanged from the four stages of heater voltages by a combination of cutting the wiring patterns 706 provided thereon, and supplies it to the recording head.
In such an ink jet recording head, however, owing to the necessity of a substrate 703 having signal contacts 704 and heater voltage ID circuits 705, it is desirable to reduce the volume of the substrate 703 as much as possible for an ink jet head associated with the advantage of the small head to achieve a further compactization of the head.
Also, it was requisite to cut the wiring patterns 706 by measuring the dispersion in heater resistances for each recording head after production, and by then selecting the optimal heater voltage on the basis of the measurement result.
On the other hand, the form of an ink tank supplied to the above-described recording head is one in which the tank is formed integrally with the recording head to be detachable together from the apparatus, or in which the tank by itself is detachable with the recording head freely detachable from the apparatus.
Recently, to provide a more compact; apparatus and to increase the life of the recording head, and to avoid environmental problems, a head tank integrated cartridge detachable therefrom having the latter construction has been noted.
In such cartridges in which the ink is arbitrarily refilled or the ink tank is periodically exchanged, there have been proposed some countermeasures against contaminants entering thereinto at the ink tank exchange.
However, the present inventors have revealed a phenomenon on the basis of many experiments that if the ink supply is arbitrarily or periodically conducted for the recording chips of recording head (e.g., one or more discharge ports, liquid channels, a liquid chamber, discharge elements such as electrothermal converting elements, and electric drive signal supply wirings), fluctuations in the ink discharge state will occur in short periods. Also, it has been found that with the constitution of exchanging a plurality of ink tanks after exhausting the ink within the ink tank to resume the recording, the stable recording period tends to be shorter than when using a large ink tank having an amount of ink sufficient for the recording chips to be recordable. In the light of this, the inventors have studied and confirmed that some failure may arise in the ink supply state before the exchange of ink tank, or the discharge elements themselves, thereby giving rise to such phenomenon.
Specifically, as one of its factors, due to characteristic changes of the discharge elements themselves which are discharge means, the change in the ink discharge amount is caused, and the minimum driving voltage is also changed, and in particular, in an ink recording head having electrothermal converters, this factor will greatly change the recording state. Accordingly, where the ink supply is arbitrarily or periodically conducted (particularly when the electrothermal converters are used), it is an important task to maintain the stable discharge performance for a long term, and to increase the life of recording head.